Fix scenarios where icon is blurry

[Simplestas]

• Using LoadIconWithScaleDown will ensure better-looking icon at non-standard DPI
• Notification area can update app icon itself for proper DPI if GetIconInfoEx will return proper module path; this doesn't work for LOAD_LIBRARY_AS_IMAGE_RESOURCE or LOAD_LIBRARY_AS_DATAFILE mapping unfortunately so use DONT_RESOLVE_DLL_REFERENCES

#495

[riverar]

I believe we tried this before and it resulted in subpar icon selection for higher standard DPIs but I'll try it out, thanks!